1. Field of the Invention
This invention relates, in general, to hydraulic couplings, and specifically to hydraulic couplings used in undersea drilling and production applications. More particularly, the invention involves a coupling having pressure balancing ports in the body of the male member for bleeding off seawater trapped in the annulus between the male and female members and avoiding implosion of the seal in the annulus upon disconnection of the members.
2. Description of the Related Art
Subsea hydraulic couplings are old in the art. The couplings generally consist of a male and a female member with sealed fluid passageways connecting therebetween. The female member generally is a cylindrical body with a relatively large diameter longitudinal bore at one end and a relatively small diameter longitudinal bore at the other. The small bore facilitates connections to hydraulic lines, while the large bore seals and slidingly engages the male member of the coupling. The male member includes a cylindrical portion at one end having an outer diameter approximately equal to the diameter of the large bore in the female member of the coupling. The male member also includes a connection at its other end to facilitate connection to hydraulic lines. When the cylindrical portion of the male member is inserted into the large bore of the female member, according to various embodiments of the device, fluid flow is established between the male and female members.
In the use of undersea couplings, the male and female members may be interconnected or disconnected while the coupling remains underwater, either manually by a diver or automatically by a diverless system as is well know to those skilled in the art. The male member and female member are generally connected to opposing plates of a manifold and are held together by bolts or hydraulic members attached to the plates of the manifolds. The male member is commonly attached to one plate, while the female member is attached to an opposing plate so as to face the male member and align with it. The male member and female member may be attached to the manifold plates using various means, such as set screws or threads. Techniques for attaching the members to such manifold plates are well known to those skilled in the art.
The large diameter bore of the female member, which slidably receives the male member, typically includes an elastomeric annular seal within an annular grove. The elastomeric seal provides a tight fit against the longitudinal surface of the male member when the members are interconnected.
Two problems have existed with the use of undersea couplings having elastomeric seals in the bore of the female member. These problems are common to both manual and automatic systems for connection and disconnection of the coupling members.
The first problem arises during connection of the male member to the female member. When the female member is subsea, the large diameter bore of the female member becomes filled with seawater. Upon connection of the members, this trapped seawater is forced into the hydraulic system through both members of the coupling, and contaminates the hydraulic system fluid.
The second problem arises during disconnection of the coupling members. When the male member is withdrawn from the large central bore of the female member, there is a resulting low pressure area or vacuum created within that bore. When the end face of the male member passes the midpoint of the elastomeric seal in the bore of the female member, the seal no longer has the outer wall of the male member to help retain the seal in its groove. At this point the pull of the vacuum and the hydraulic pressure of seawater trying to get past the elastomeric seal implode the seal out of the groove and into the annulus between the male and female members. The vacuum also increases the difficulty of manually disengaging the male from the female member. This resistance to disengagement due to the vacuum is magnified when multiple couplings on manifold plates are disengaged. The present invention solves each of the above problems.